Anapsida
Anapsida | ||||||||||||||||
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Obsolete systematic group The taxon dealt with here is not part of the systematics presented in the German-language Wikipedia. More information can be found in the article text. |
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Systematics | ||||||||||||||||
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Scientific name | ||||||||||||||||
Anapsida | ||||||||||||||||
Williston , 1917 |
According to the traditional view, the Anapsida are a subclass of reptiles whose nominal characteristic is the anapsid skull, i.e. a skull without a skull or temporal window in the cheek or temple region (tempora). According to the classic Anapsida concept, the non-possession of temple windows is an indication of a closer relationship between the turtles and a number of certain fossil terrestrial vertebrates of the Permian and Triassic , which also have an anapsid skull.
Although there was no question that the anapsid skull was an original feature of the terrestrial vertebrates and therefore not well suited for characterizing one of their systematic subgroups, the established group term anapsida was initially retained in the recent past. More modern, cladist-based concepts defined the Anapsida as the basal monophylum of the amniotes , which includes the turtles and their closest fossil relatives, whereby different investigators came to different results with regard to the composition of this clade. However, since a less basal position of the turtles is now considered likely, the group term anapsida is used less and less in current scientific literature.
etymology
Anapsida is a compound from α privativum and the Greek word ἁψίς ( apsis , "arch", "vault"), which together means "bowless". It indirectly refers to the lack of temporal or temple windows in the representatives of this group. Temporal windows are typical of the skulls of certain other amniotic groups and are partially delimited by relatively narrow bone bridges, the temporal, temporal or zygomatic arches. Since anapsids have no temporal windows, they consequently also have no temporal arches and are therefore "bowless".
Classic concept
After Henry Osborn proposed the division of reptiles into Diapsida and Synapsida in 1903 , which was primarily based on the formation of the temporal region of the skull, Samuel Williston published an article in 1917 in which, on the same principle as Osborn, he divided the reptilia into recommended four main groups: Anapsida , Synapsida , Diapsida, and Parapsida . The Anapsida were primarily defined by the complete absence of temporal windows and contained the turtles and a number of fossil, reptile-like terrestrial vertebrates, which at that time were summarized under the term Cotylosauria . This conception of the Anapsida essentially existed until the second half of the 20th century, when the cotylosaur concept was later abandoned, and some authors outsourced the turtles as a separate subclass closely related to the Anapsida, so that the Anapsida was now a collective group for everyone as "cotylosaurs" but now considered as real reptiles formed groups.
Cladistic concept
In the second half of the 20th century, and especially from the 1990s, the investigation of the relationships between living things was increasingly carried out using cladistic methods . This change also had an impact on the biological system , as the organisms were now divided into groups strictly according to the relationship hypotheses. This also had an impact on the anapsida concept. Among other things, the classic concept of "Reptilia" was discarded, because according to this, the reptiles are not a natural family group ( Monophylum ), but a Paraphylum , because mammals and birds, descendants of land vertebrates traditionally grouped under "Reptilia", were not included. Therefore, the classic concept of Reptilia has been replaced by the concept of Amniota.
Monophyletic groups with a basal position within the amniota, which the turtles contained, were now called anapsida. Since different processors came to different results in their analyzes, the composition and position of the Anapsida fluctuated relatively strongly. In addition to the turtles, they once contained the captorhinids and another time a number of basal amniotes, which were and are also summarized under the term parareptiles . Despite such differences, these clades still agreed to a certain extent with the traditional conception of the anapsids, because both the captorhinids and most parareptiles have anapsic skulls and were classified among the cotylosaurs at the time. The name Anapsida for these clades was justified.
However, recent studies of the relationship between the turtles have shown that the turtle line does not change shortly after the synapsid and sauropsid lines have separated from the sauropsid line (reptiles in the modern, cladistic understanding, including birds; group also known as Reptilia) split off, but later. The closest fossil relatives of the turtles would therefore be neither parareptiles nor captorhinids, but a group within the diapsids. In such a scenario, the group term anapsida is in fact no longer justified and due to the growing acceptance of the diapsid hypothesis among biologists and paleontologists in the recent past, it is disappearing from the scientific literature.
Systematics
Classic concept
According to Williston (1925):
- Subclass Anapsida
- Order † Cotylosauria
- Subordination Seymouriamorpha 1
- Family Seymouridae
- Subordination Diadectosauria
- Family Diadectidae 1
- Family Bolosauridae 4
- Suborder labidosauria
- Family Captorhinidae 2
- Family Pariotichidae 3
- Stephanospondylidae family 1
- Subordination Pantylosauria 3
- Family Pantylidae
- Subordination Pariasauria 4
- Family Pariasauridae
- Subordination Procolophonia 4
- Family Procolophonidae
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inc. sed. :
- Family Sauravidae 5
- Gymnarthridae family 3
- Family Limnoscelidae 1
- Family Elginiidae 4
- Subordination Seymouriamorpha 1
- Order † Eunotosauria 4
- Order Testudinata or Chelonia (tortoises)
- Order † Cotylosauria
According to Kuhn (1958):
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Anapsida
- Order † Anthracosauria
- Order † Cotylosauria
- Subordination Seymouriamorpha 1
- Subordination Diadectomorpha 1
- Subordination Procolophonia 2
- Subordination Pareiasauria 2
- Subordination Captorhinida 3
- Order † Microsauria 4
- Order turtles (Testudines)
According to Carroll (1988):
- Subclass † Anapsida
- Order Captorhinida
- Suborder Captorhinomorpha
- Family Protorothyrididae 1
- Family Captorhinidae 2
- Family Batropetidae 3
- Family Bolosauridae 4
- Family Acleistorhinidae 4
- Subordination Procolophonia 4
- Superfamily Procolophonoidea
- Family Nyctiphruretidae
- Family Procolophonidae
- Family Sclerosauridae
- Superfamily Procolophonoidea
- Subordination Pareiasauroidea 4
- Family Rhipaeosauridae
- Family Pareiasauridae
- Family Millerettidae
- Suborder Captorhinomorpha
- Order Mesosauria 4
- Family Mesosauridae
- inc. sed .:
- Order Captorhinida
According to Carroll (1988), the turtles form their own subclass.
Cladistic concept
According to Gauthier et al. (1988):
Amniota |
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According to Modesto (2000):
Amniota |
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Individual evidence
- ^ Henry F. Osborn: On the primary division of the Reptilia into two subclasses, Synapsida and Diapsida. Science. Volume 17, No. 424, 1903, pp. 275-276, doi: 10.1126 / science.17.424.275-b (Note: the first publication of the taxon names Diapsida and Synapsida, February 1903).
- ^ Henry F. Osborn: The reptilian subclasses Diapsida and Synapsida and the early history of the Diaptosauria. In: Memoirs of the American Museum of Natural History , Volume 1, No. 8, 1903, pp. 451-507, hdl: 2246/5739 (note: an extensive follow-up to the Science article, November 1903).
- ^ Samuel W. Williston: The Phylogeny and Classification of Reptiles. In: The Journal of Geology. Vol. 25, No. 5, 1917, pp. 411-421, JSTOR 30062555 .
- ↑ a b Oskar Kuhn: amphibians and crawling animals of the past (= Die Neue Brehm-Bücherei. Issue 217). 2nd, unchanged edition, reprint of the 1st edition from 1958. Westarp-Wissenschaften, Hohenwarsleben 2004, ISBN 3-89432-663-8 .
- ^ A b Robert L. Carroll: Vertebrate Paleontology and Evolution. WH Freeman and Co., New York 1988, ISBN 0-7167-1822-7 , p. 615.
- ^ Edwin H. Colbert: The Age of Reptiles. Dover Publications, Mineola NY 1997 (expanded and revised new edition of the original work from 1965), ISBN 0-486-29377-7 , p. 223.
- ^ A b Jacques A. Gauthier, Arnold G. Kluge, Timothy Rowe: The early evolution of the Amniota. In: Michael J. Benton (Ed.): The phylogeny and classification of the tetrapods. Volume 1: Amphibians, reptiles, birds. Systematics Association Special Volume. No. 35A, 1988, pp. 103-155.
- ↑ a b Sean P. Modesto: Eunotosaurus africanus and the Gondwanan Ancestry of Anapsid Reptiles. In: Palaeontologia africana , Volume 36, 2000, ISSN 0078-8554 , pp. 15-20.
- ↑ Rafael Zardoya, Axel Meyer: The evolutionary position of turtles revised. Natural sciences. Vol. 88, No. 5, 2001, pp. 193-200, doi: 10.1007 / s001140100228 .
- ^ Samuel W. Williston, The Osteology of the Reptiles. Harvard University Press, Cambridge MA 1925, doi: 10.5962 / bhl.title.45170 .
Web links
- Michel Laurin, Jacques A. Gauthier: Phylogeny and Classification of Amniotes . Tree of Life web project
- Anapsida. Palaeos - Life through deep time (there as clade, more or less synonymous with Parareptilia)